In order to have an article manipulated correctly and in a stable state in a robot, it is important that the article be strictly aligned with or centered with respect to the gripper assembly which forms part of the robot. Difficulties are however encountred to acheive such strict alignment between the gripper assembly and the article to be handled. If the article has failed to be correctly centered with respect to the gripper assembly, one of the fingers forming part of the gripper assembly would be first brought into contact with the article and cause the article to unduly move with respect to the gripper assembly and would thus impart an unnecessary force or impact to the article. If the article to be handled is implemented a basket containing wafers, the wafers may be caused to slide on the surfaces of the basket supporting the wafers and produce fine particulates or may be dislocated from the proper positions on the basket.
A prime object of the present invention is to provide an improved gripper assembly which is free from these problems of a known gripper assembly, typically a gripper assembly of a robot used for semiconductor fabrication processes.